This paper highlights photonic crystal Mach-Zehnder structures that use W1 channel waveguide in 2D hexagonal photonic crystal structures and have channel orientation along GammaK directions. The FDTD software, Fullwave, from RSoft has been used to simulate photonic crystal channel waveguides, Y-junction and bend in order to design a complete Mach-Zehnder interferometer structure in epitaxial II-V semiconductor material for operation at 1550nm. It is our near-future aim to use these Mach-Zehnder structures as the basis for thermo-optic switching devices. Electro-Beam lithography (EBL) and reactive ion etching (dry-etching) processes have been used to fabricate these devices